I see that PCEM by default wants to add a CDROM drive to E: and that on newer machines that will add it to the 2nd native IDE controller (master).

But what does it do on older machines with just one controller? Does it add its own BIOS like an expansion card? I've noticed the CD drive is still detected and usable even though there's no secondary controller in these machines.

First, I'm not sure what you call "older machines" all PCem machines are more than 20 years old...
By default, PCem assigns D: to the CDROM... but that can be easily configured in the menu
For what I know, IDE controllers do not have an independent bios

PCem always emulates two IDE controllers. The secondary won't be used by the BIOS in older machines, but CD-ROM drivers can still access it. This was a real setup available back in the day - many sound cards (eg SB16) came with an IDE port which could be used for CD-ROM.

Ah, I thought PCEM must be injecting something since as you say the BIOS on those machines can't see anything.

omarsis81 wrote:First, I'm not sure what you call "older machines" all PCem machines are more than 20 years old...
By default, PCem assigns D: to the CDROM... but that can be easily configured in the menu
For what I know, IDE controllers do not have an independent bios

By older I mean almost all 286/386 machines that include IDE as standard, they only provide two IDE slots. The newer PCs that PCEM emulates have primary and secondary controllers giving four IDE drives.

teppic wrote:Ah, I thought PCEM must be injecting something since as you say the BIOS on those machines can't see anything.

omarsis81 wrote:First, I'm not sure what you call "older machines" all PCem machines are more than 20 years old...
By default, PCem assigns D: to the CDROM... but that can be easily configured in the menu
For what I know, IDE controllers do not have an independent bios

By older I mean almost all 286/386 machines that include IDE as standard, they only provide two IDE slots. The newer PCs that PCEM emulates have primary and secondary controllers giving four IDE drives.

One physical IDE port can support two IDE drives, one primary and one secondary. So those two physical IDE slots on old motherboards provided for a total of two primary and two secondary IDE drives.

teppic "as was common for all machines from the pentium onwards until SATA replaced IDE" , on that i must disagree, in my opinion the most had 2 ports, like most of socket 7 motherboards and most slot one motherboards. i had plenty of them and one port was unusual, go to ebay, You got plenty pictures of those motherboards , and You will see. dont know about PIII motherboards onward, You might be right there, but up to P2 i m sure of it.

I don't see the disagreement here. Most Pentium and later motherboards had 2 IDE ports for 4 IDE devices, most 486 and earlier had either no IDE ports on the motherboard, and used an IO card with 1 IDE port and _occasionally_ 2, or had 1 or _occasionally_ 2 ports on the motherboard. That's basically exactly what both you and teppic are saying.